Animating dynamic geo-social networks
Understanding the structure and evolution of dynamic spatial networks is crucial for various fields such as genealogy, epidemiology and urban planning. The layout of a dynamic spatial network is formed by the geographic coordinates of nodes (individuals) and edges that metaphorically represent relations (e.g., family, friendship). Nodes and edges of such a network evolve (change) over time. Dynamic spatial networks are usually large and multi-relational because there can be different type of relations (e.g., family, friendship, membership in an organization). Visualization can potentially play a key role in analyzing and understanding dynamic networks.
By allowing user interactions and controls, animation can facilitate the discovery of community structures and comprehension of structural changes in a dynamically evolving network embedded in geographic space. Below are examples of trajectory animation of a set of dynamic geo-social networks.
Trajectories of animals in the Starkey Project
This is a web-based geovisualization framework that can animate geographic moves of animals in Starkey Project. Each node represents a species and the colors green is used for elk, blue for deer and red for cattle. The animation of the different species help discover grouping and dispersion of animals across a variety of locations.
The Starkey Project is one of the most comprehensive field research projects ever attempted. Studies examine key questions about elk, timber, cattle, deer, recreation uses and nutrient flows on National Forests. An automated radio telemetry system automatically tracks locations with computers, which requires less fieldwork from biologists. The system uses Loran-C technology, the same technology used by the Coast Guard, Navy, and other maritime vessels to pin-point their locations in the ocean. Regularly monitoring animal movements helps researchers answer questions about the response of deer and elk to intensive timber management, cattle grazing, vehicle traffic and hunting on National Forests. The Loran-C tracking system provides the most accurate, efficient and cost-effective vehicle, for recording animal movements over several years.
Migration of 9 families in the U.S.
This is a web-based geovisualization framework that animates geographic moves of 9 families in the U.S. over a 300 year period. Family tree data derived from genealogical sample from the U.S. North include 9 families, 4481 individuals and approximately 11,000 geocoded moves. The system consists of a background map and a widget to control the family tree animation. An animation for each of the 9 families can be played and paused at different map extents. Nodes are placed according to their geographic location. As a person moves a trajectory line is drawn to illustrate the path that the individual followed throughout his life. The color of the node and the trajectory line is red if the individual is alive at the current time of the animation. If the individual dies the color of both the node and the trajectory turns into blue.
The distribution of the number of moves vary over time and a peak is observed mid-19th century. As a result of the temporal distribution of moves, when the animation is played at a constant speed, much fewer moves occur at most times whereas a lot of moves occur in a short period of time. To address the problem, animation speed can be set to be variable which slows down and speeds up the animation proportional to the amount of moves occurring within the current time frame. To visualize the distribution of moves over time, a histogram can also be accessed within the widget.
Dynamic relations in a geo-social network
This is a web-based geovisualization framework that can animate the parent-child relations in the same family network shown in the above example. Nodes are placed according to their geographic location and edges are drawn to represent parent-child relations. Each edge follows the right-hand rule, starts curvy from the parent and becomes straight towards the child.